1. Field of the Invention
This invention relates broadly to a feed means for feeding elongate articles hereinafter referred to as the type described, comprising an elongate shank having an enlarged head at or adjacent one end thereof, the feed means feeding said articles in succession and in a predetermined orientation at high speed to a receiving station. By high speed we mean at least 300 articles per minute and preferably at least 1000 articles per minute. More particularly, but not exclusively, the invention relates to a machine for assembling blind rivets comprising a hollow, headed, rivet and a headed mandrel incorporating a feed means for feeding at high speed the headed mandrels in succession and in a predetermined orientation to a receiving station of the machine.
2. Description of the Prior Art
Hitherto elongate articles of the type described have been fed by a feed means comprising a disc having a plurality of notches in its periphery and the articles being fed to the periphery of the wheel for entry into successive notches along a suitably inclined track. Such a feed means has been found to be not entirely satisfactory due to a tendency for the heads of the articles to wedge together due to the weight of articles in the track and because entry of articles into a notch is dependent solely upon the force of gravity. In addition, if an article is bent then part of the length of the article can engage in a notch of the disc and another part remain engaged with the track causing jamming of the feed means.
DE No. 182,407 is a proposal, never put into practice so far as the Applicants are concerned, for an alternative form of feed means which is capable of operation only at low speeds, i.e. speeds of less than 300 articles per minute. The German Specification discloses feed means for feeding elongate articles in succession and in a predetermined orientation to a receiving station and includes an inclined track comprising a pair of parallel shoulders affording a slot therebetween so that, in use, a head of an article of the type described can be supported on the shoulders with its shank depending downwardly through the slot and, at the lower end of the slot, there being a rotatable feed member having a helical groove of such configuration as to permit a lowermost article in the track to enter the groove and be transported transversely away from the track between the feed member and the lower end of the track.
It is self evident to persons skilled in the art that the machine described in the German Specification is incapable of operating at feed rates suitable for modern industrial practice feeding at least 300 articles per minute. The reasons which would lead persons skilled in the art to this conclusion include the reliance on gravity feed, the use of a reciprocating linkage which precludes practical operation at high speeds and the fact that at the turn of the Century rates of production generally were not such as to lead a skilled person to expect a feed rate of at least 300 articles per minute.